1. Field of the Invention
The present invention relates in general to a filter device for compressed air which has filter means having suitable packings accommodated in suitable sleeves, and more particularly to such a filter device for compressed air in which the packings can be easily and quickly replaced.
2. Discussion of the Related Art
Generally, passages for supplying compressed air to various pneumatically operated components used in various factories and atomic plants, for example, are provided with filter devices for removing water and oil contained in a flow of the compressed air, for the purpose of protecting the pneumatic components or improving the performance of those components.
One type of such a filter device for compressed air is disclosed in laid-open Publication No. 62-1763 of examined Japanese Patent Application, which is constructed as shown in FIG. 14. This disclosed filter device includes two kinds of filter means. Namely, the filter device 90 includes first filter means 12 having a suitable first packing 93 accommodated in a first sleeve 92 thereof, and second filter means 14 having a suitable second packing 95 accommodated in a second sleeve 94 thereof. The first and second filter means 12, 14 are disposed parallel with each other on a trap chamber 96 having a suitable volume capacity, so as to extend in the vertical direction from the trap chamber 96, such that each of the first and second filter means 12, 14 communicates with the trap chamber 16.
The trap chamber 96 consists of a guide passage portion 98 and a drain portion 100 which are fixed to each other by suitable bolts. The guide passage portion 98 communicates with the first and second filter means 12, 14, and has a guide passage 44 formed therein, so that the compressed air is fed through the guide passage 44 from the first filter means 12 to the second filter means 14. The lower open end of the guide passage 98 is fluid-tightly closed by the drain portion. To the bottom wall of the drain portion 100, there is attached a drain device in the form of a weep valve 102 through which a liquid separated from the compressed air by the first filter means 12 and accumulated in the trap chamber 96 is discharged out of the filter device 90.
On the first and second filter means 12, 14, there is disposed a manifold 108 which includes an inlet passage portion 104 and an outlet passage portion 106. The inlet passage portion 104 has an inlet passage 37 formed therein, through which the compressed air is introduced into the filter device 90. The outlet passage portion 106 has an outlet passage 39 formed therein, through which the compressed air is fed out of the filter device 90. The inlet and outlet passages 37, 39 communicate with the first and second filter means 12, 14, respectively.
The first and second filter means 12, 14, the trap chamber 96 and the manifold 108 are assembled together and fixed to each other by a plurality of bolts 110 which extend through the manifold 108 and which are screwed in the guide passage portion 98 of the trap chamber 96. According to this arrangement, the compressed air entering the inlet passage 37 of the manifold 108 is fed through the first filter means 12 into the trap chamber 96, and then through the second filter means 14 into the outlet passage 39 of the manifold 108, whereby an air passage for the compressed air is formed through the filter device 90.
In the filter device 90 constructed as described above, usually, a wound wire mesh fabric formed of stainless steel fibers or other metallic materials is used for the first packing 93 of the first filter means 12, so that vapor and/or liquid particles like water and oil contained in the compressed air are condensed or coalesced as the compressed air passes through the first filter means 12. For the second packing 95 of the second filter means 14, usually, a wound fabric mesh formed of cotton fibers is used, so that the liquid particles contained in the compressed air are absorbed and vaporized as the compressed air passes through the second filter means 14.
Thus, in the filter device 90 disclosed in the above-indicated publication, the vapor and/or liquid particles are condensed or coalesced as the compressed air is introduced into the trap chamber 96 through the inlet passage 37 of the manifold 108 and the first filter means 12, so that the vapor and/or liquid particles are separated from the compressed air. Further, the compressed air from which the vapor and/or liquid particles have been thus separated is introduced into the second filter means 14 through the trap chamber 98, so that the amount of the liquid particles remaining in the compressed air is minimized.
The first and second packings 93, 95 constituting the first and second filter means 12, 14, respectively, are required to be replaced with clean ones when the packings 93, 95 get clogged with dust and/or grease. The replacement requires the following operations.
First, the plurality of bolts 110 serving to connect the first and second filter means 12, 14, the manifold 108 and the trap chamber 96 into an integral assembly are all removed, and the assembly is disassembled into the four parts. Secondly, the clogged first and second packings 93, 95 which are accommodated in the first and second sleeves 92, 94, respectively, are replaced with clean ones. And then, the first and second filter means 12, 14, the trap chamber 96 and the manifold 108 are assembled together and fixed to each other, as described before, by screwing the plurality of bolts 110 in the respective positions.
That is, in the conventional filter device 90 disclosed in the above-identified publication, each time the first and second packings 93, 95 of the first and second filter means 12, 14 are replaced, the device 90 has to be disassembled into the parts before the replacement, and the parts have to be reassembled into the device 90 after the replacement.
The filter device 90 is advantageously used in various factories, atomic plants and medical field owing to its high filtering performance. However, the filter device 90 requires the above-described operations for replacing the first and second packings 93, 95, which operations are cumbersome and time-consuming, as described above. There is still a room for improvement in this filter device 90.